Intel Baytrail has been observed sometimes to hang
if host controllers are using DMA while deep C-states
are used. Workaround that by specifying a maximum
DMA latency that will prevent deep C-states.
Unfortunately, host controller ACPI HIDs are not unique
to Baytrail, so the CPU must be identified.
Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
---
drivers/mmc/host/sdhci-acpi.c | 32 ++++++++++++++++++++++++++++++++
1 file changed, 32 insertions(+)
diff --git a/drivers/mmc/host/sdhci-acpi.c b/drivers/mmc/host/sdhci-acpi.c
index 22d929f..eaff09f 100644
--- a/drivers/mmc/host/sdhci-acpi.c
+++ b/drivers/mmc/host/sdhci-acpi.c
@@ -43,6 +43,24 @@
#include "sdhci.h"
+#ifdef CONFIG_X86
+#include <asm/cpu_device_id.h>
+static bool sdhci_acpi_on_byt(void)
+{
+ static const struct x86_cpu_id byt[] = {
+ { X86_VENDOR_INTEL, 6, 0x37 },
+ {}
+ };
+
+ return x86_match_cpu(byt);
+}
+#else
+static bool sdhci_acpi_on_byt(void)
+{
+ return false;
+}
+#endif
+
enum {
SDHCI_ACPI_SD_CD = BIT(0),
SDHCI_ACPI_RUNTIME_PM = BIT(1),
@@ -146,6 +164,14 @@ static const struct sdhci_acpi_chip sdhci_acpi_chip_int = {
.ops = &sdhci_acpi_ops_int,
};
+static void sdhci_acpi_int_dma_latency(struct sdhci_host *host)
+{
+ if (sdhci_acpi_on_byt()) {
+ host->dma_latency = 20;
+ host->lat_cancel_delay = 275;
+ }
+}
+
static int sdhci_acpi_emmc_probe_slot(struct platform_device *pdev,
const char *hid, const char *uid)
{
@@ -164,6 +190,8 @@ static int sdhci_acpi_emmc_probe_slot(struct platform_device *pdev,
sdhci_readl(host, SDHCI_CAPABILITIES_1) == 0x00000807)
host->timeout_clk = 1000; /* 1000 kHz i.e. 1 MHz */
+ sdhci_acpi_int_dma_latency(host);
+
return 0;
}
@@ -178,6 +206,8 @@ static int sdhci_acpi_sdio_probe_slot(struct platform_device *pdev,
host = c->host;
+ sdhci_acpi_int_dma_latency(host);
+
/* Platform specific code during sdio probe slot goes here */
return 0;
@@ -194,6 +224,8 @@ static int sdhci_acpi_sd_probe_slot(struct platform_device *pdev,
host = c->host;
+ sdhci_acpi_int_dma_latency(host);
+
/* Platform specific code during sd probe slot goes here */
return 0;
--
1.9.1
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